The present invention concerns mercaptoalkyl alkoxysilanes which are free of malodorous byproducts, as well as a method for the permanent removal of these malodorous byproducts.
Mercaptoalkyl alkoxysilanes have many applications in the chemical industry. They are suitable for use, for example, as adhesivizers for the solution of special problems of adhesion between inorganic and organic substances or for the modification of silicones to broaden their applications. Disadvantageous in all applications is the strong, unpleasant odor which this product has on the basis of contaminating byproducts resulting from the technical production of these compounds. The mercaptoalkyl alkoxy-silanes are prepared, as a rule, by the reaction of halogen alkyl alkoxysilanes with thiourea and ammonia by the method described in German Federal Pat. No. 20 35 619. The unpleasant-smelling byproducts resulting from this method of preparation are contained in the end product in such small amounts that removing them by the obvious method of fractional or repeated distillation does not achieve the desired success, and the distillates obtained even by repeated fractional distillation are still extremely odorous and are not salable in this form.
The problem therefore existed of treating mercaptoalkyl alkoxysilanes such that they no longer have an unpleasant smell and the freedom from unpleasant odors lasts for a long time--several months if possible.